Multicylinder pump for liquids



United States Patent [72] Inventors Vladimir Ivanovich Roschupkin;

Semen Lvovich Zalkin; Stanislav Vasilievich Lovchev, Moscow, U.S.S.R. 733,911

June 3, 1968 Oct. 6, 1970 Gosudarstvenny Nauchno-Issleduvatelsky l Proektny lnstitut Neftyanogu Mashinostmenia,

Moscow, U.S.S.R.

[2i App]. No. [22] Filed [45] Patented [73] Assignee [54] MULTICYLINDER PUMP FOR LIQUIDS 3 Claims, 3 Drawing Figs.

[52] US. Cl 92/60,

[51] mm ..F04b17/00, FO4bll/OO 501 FieldofSearch 103/44, 44w,49,52,223

[56] References Cited UNITED STATES PATENTS 2,023,405 12/1935 Qarroi] 103/44 2,811,925 11/1 57 Crookston lO3/49X Primary Examiner- Robert M Walker AlI0rney-Waters, Roditi and Schwartz ABSTRACT: A multicylinder pump in which the chambers are connected via additional cylinders to a source ofa resilient medium from which the chambers are separated by movable partitions.

Patented Oct. 6, 1970 3,532,029

Sheet I of 2 Patented Oct. 6, 1970 3,532,029

Sheet 2 of2 MULTICYLINDER PUMP FOR LIQUIDS The present invention relates to hydraulic machines and more specifically it relates to piston-type and plunger-type multicylinder pumps for liquids.

Known in the art are piston and plunger-type multicylinder pumps for liquids wherein the pump capacity is controlled by changing the volume of the working chambers by connecting each chamber to a separate vessel filled with a resilient medium such as compressedgas, this vessel communicating with a source of pressure. The working chamber is separated from the resilient medium by means of a movable partition, for example a piston, and is provided with a device for limiting the piston travel on the suction stroke.

It is an established fact that the working element of such a pump, for example the piston, is subjected on the suction stroke to an additional load occasioned by the pressure of the resilient medium. If the pump capacity is at the zero level then the piston overcomes the total pressure difference range of the resilient medium both on the discharge and suction strokes.

In high-pressure pumps handling polluted liquids, for example clayey solution, this phenomenon may lead to a premature failure of the pump working piston and, consequently, to a reduced reliability of the installation as a whole.

Besides, the widely used H.P. multicylinder piston pumps are characterized by nonuniform delivery causing pressure pulsations at the discharge side. The nonuniformity of the pump delivery cannot be reduced by connecting a separate vessel with a resilient medium to each working chamber of the pump unless it is possible to insure a low degree of compression of the resilient medium in said vessel during the controlled-capacity operation of the pump.

However, such a solution fails to prove effective in HP. pumps since it calls for an increased volume of the separate vessels with a resultant increase in the weight and overall dimensions of the pump.

On the other hand, small size of the separate vessel limits the range of the pump capacity control.

An object of the present invention resides in providing a multicylinder pump whose working pistons are relieved by the pressure of the resilient medium during controlled-capacity operation which insures reliable operation of the pump handling polluted liquids.

Another object of the invention consists in providing a multicylinder pump wherein the capacity control insures uniform delivery at the discharge side.

Still another object of the invention resides in providing a multicylinder pump with a small vessel containing a resilient medium, said vessel allowing the pump capacity to be controlled within broad limits (from a maximum to zerodelivery).

In compliance with these and other objects, there is provided in accordance with the invention a multicylinder pump for liquids, whose capacity is controlled by connecting to each working chamber a vessel with a resilient medium, said vessel communicating with a source of pressure and separated from the working chamber by a movable partition.

According to the invention, in the pump, use is made of double-acting cylinders each working chamber of said cylinders communicating with a vessel common for all the cylinders filled with a resilient medium and communicating with a source of pressure, each of said working chambers being separated from the resilient medium by an independent movable partition.

It is preferred to make the common vessel for the resilient medium in the form of intercommunicating cylinders, each accommodating two independent movable partitions. The

number of said cylinders should be equal to that ofthe double acting cylinders.

It is also preferred to make the common vessel for the resilient medium in the form of intercommunicating cylinders each accommodating one movable partition. the number of said cylinders being equal to that of the working chambers of the pump double-acting cylinders.

The multicylinder pump according to the invention relieves the pump working piston of the pressure differential during the controlled-capacity operation; insures maximum capacitycontrol limits and uniform delivery at the discharge side in spite of a small volume of the vessel with the resilient medium; maintains a preset capacity and controls it automatically without changing the number of the pump double strokes and the dimensions of the cylinder; and raises to a maximum the efficiency of the pump installation.

Given below is a detailed description of the invention by way of example with reference to the appended drawings in which:

FIG. 1 is a diagram of a multicylinder pump according to a first embodiment of the invention;

FIG. 2 is a diagram of a multicylinder pump according to a second embodiment; and

FIG. 3 is a diagram of a multicylinder pump, according to a third embodiment.

The multicylinder pump, according to the first embodiment, incorporates two double-acting cylinders 1 (FIG. 1) whose working pistons 2 are connected by a rod 3 to a reciprocating drive (omitted in the drawing). The cylinder 1 is divided by the piston 2 into two working chambers 4 and 5. Each working chamber communicates with a common vessel 6 for the two cylinders 1, said vessel being filled with a resilient medium and communicating with a source of pressure 7. The working chamber of the pump is separated from the resilient medium by a movable partition, for example a piston 8 sliding in a cylinder 9. The volume of the cylinder 9 should be equal to or larger than that displaced by the working piston 2 on the discharge stroke. Installed on the bottom of the cylinder 9 is a device 10 limiting the travel of the piston 8.

In the second embodiment of the invention, the common vessel 6 filled with a resilient medium is formed by two cylinders ll (FIG.2) intercommunicating through a pipe 12. Each cylinder 11 communicates with one of the working chambers 4, 5 of the double-acting cylinder 1 and has two pistons 8, the number of the cylinders 11 being equal to that of the doubleacting cylinders 1.

ln the third embodiment of the invention, the common vessel 6 filled with the resilient medium is formed by four cylinders l3 (FIG.3) intercommunicating through a pipe 14. Each cylinder I3 communicates with one of the working chambers 4, 5 of the double-acting cylinder 1 and has one piston 8. The number of the working cylinders 13 is equal to that of the working chambers of the pump double-acting cylinders.

If the common vessel 6 with the resilient medium is formed by two cylinders 11 (FIG.2) or four cylinders 13 (FIG.3), the corresponding pipes 12 and 14 must insure a free flow of the resilient medium from one cylinder into the other and back. It is only in this case that the equality of pressure of the resilient medium on the pistons 8 during the controlled-capacity operation can be obtained.

The multicylinder pump operates as follows.

The working piston 2 (FIG. 1) on its discharge stroke displaces an amount of liquid from the working chamber 4, this amount being equal to the product of the piston area and the length of its stroke. The displaced liquid is divided into two portions. One portion flows through the valve 15 into the pipe 16 at the discharge side while the other portion moves the piston 8 and enters the cylinder 9. The amount of liquid entering the cylinder 9 depends on the pressure of the resilient medium in the common vessel 6. If the initial pressure of the resilient medium in the common vessel 6 is higher than pressure at the discharge side of the pump, the pistons 8 in the initial position contacts the limiting device 10 and the pump runs at a maximum capacity. If the initial pressure of the resilient medium is lower than the pressure at the discharge side of the pump, the pistons 8 start moving. This reduces the volume occupied by theresilient medium in the common vessel 6 and the pressure of said medium becomes equal to the pressure at the discharge side of the pump. By controlling the initial pressure of the resilient medium in the common vessel 6 by means of the source of pressure 7, it becomes possible to control the discharge pressure and the capacity of the pump.

However, the amount of the resilient medium in the vessel 6 for the preset capacity remains practically unchanged since the pistons 8 in the cylinders 9, communicating with the working chambers 4 and 5, move simultaneously in opposite directions (shown by arrows in FIG. 1). A slight difference in the speeds of the pistons does not exert any perceptible influence upon the volume of the resilient medium in the common vessel 6.

Hence, the pressure of the resilient medium in the common vessel 6 can grow higher than the initial pressure when the pump capacity drops, though for any preset capacity this pressure remains practically constant during the pump operation. This insures a uniform delivery and a continuous (nonpulsating) flow at the discharge side and allows the use ofthe smallest possible common vessel with the resilient medium.

As the working piston 2 of the pump completes the discharge stroke in the chamber 4 and comes to the dead point, the amount of liquid in the cylinder 9 connected to said chamber will reach a maximum and the piston 8 in this cylinder will be farthermost from the initial position. At this instant the discharge valve 15 will close and the working piston 2 will start moving in the opposite direction. In this case the working piston 2 will displace the liquid from the chamber 5 at the same time evacuating the space in the chamber 4, said space being filled with the liquid forced from said cylinder 9 by the pressure of the resilient medium. The pressure in the chamber 4 will be practically equal to that in the chamber 5. When, at a certain point of the stroke of the working piston 2, the piston 8 in the cylinder 9 communicating with the chamber 4 comes to the initial position and contacts the limiting device 10 on the bottom of the cylinder 9, the pressure in the working chamber 4 will drop and the suction valve 17 will be opened by the excessive atmospheric pressure. During the rest of the stroke of the working piston 2 the chamber 4 will be filled with liquid from the pipe 18 at the suction side.

Hence, the resilient medium relieves the working piston 2 of the pressure differential in the chambers 4 and 5 within a part of its stroke preceding the opening of the suction valve 17.

Besides, the packing 19 of the rod 3 on the suction stroke in the working chamber 5 is also relieved of the pressure differential forces since the pressure of the resilient medium in the cylinder 9 connected to the chamber 5 is directed contrary to the forces of the initial tension of the packing 19 of the rod 3 originated during the packing installation. At zero capacity of the pump, the working piston 2 and the packing 19 of the rod 3 are completely relieved of the pressure differential forces in the course of operation.

The operating principle of the pumps made according to the second and third embodiments is identical with that of the first embodiment.

In describing the present embodiment of the invention the terms are used in their narrow sense for the sake of lucidity. However, the invention is not confined to the narrow sense of the terms used and it will be understood that each of said terms embraces all the equivalent elements functioning similarly and employed for the same purposes.

While a specific embodiment of the invention has been disclosed in the description, it will be understood that various modifications and changes within the spirit and the scope of the invention may occur to those skilled in the art.

These changes and modifications can be resorted to without departing from the function or scope of the invention as hereinafter defined by the appended claims.

We claim:

1. A multicylinder controlled-capacity pump for liquids comprising: double-acting cylinders; pistons in said cylinders and dividing the same into working chambers; a single common vessel for said cylinders filled with a resilient medium and communicating with each working chamber of said doubleacting cylinders; independent movable partitions separating each of said working chambers of the double-acting cylinders from the resilient med|um of said common vessel; and a source of pressure communicating with said common vessel.

2. A multicylinder pump as claimed in claim 1 wherein the common vessel filled with the resilient medium includes intercommunicating cylinders each accommodating two of said independent movable partitions, the number of the latter said cylinders beingequal to that of the double-acting cylinders.

3. A multicylinder pump as claimed in claim 1 wherein the common vessel filled with the resilient medium includes intercommunicating cylinders each accommodating one said movable partition, the number of the latter said cylinders being equal to the number of the working chambers of the double-acting cylinders. 

